Thermostatic expansion valve having pressure responsive means for varying the superheat setting thereof



y 3, 1951 F. Y. CARTER 2,558,930

THERMOSTATIC EXPANSION VALVE HAVING PRESSURE RESPONSIVE MEANS FOR VARYING THE SUPERHEAT SETTING THEREOF Filed May 29, 1947 FIGJ . 'IIIIIIIIIIIIII- 5 I INVENTOR.

Mk M BY W KM - AIIQBN Patented July 3, 1951 THERMOSTATIC EXPANSION VALVE HAV- ING PRESSURE RESPONSIVE MEANS FOR VARYING THE I SUPERHEAT SETTING THEREOF Franklyn Y. Carter, Dearborn, Mich, assignor to Detroit Lubricator Company, Detroit, Mich., a

corporation of Michigan Application May 29, 1947, Serial No. 751,321

This invention relates to new and useful improvements in thermostatic expansion valves.

An object of this invention is to provide means operable to reduce variation in the superheat setting of a thermostatic expansion valve.

Another object of this invention is to provide means for adjusting the superheat in accordance with the differential of pressures across the evaporator to be supplied by the valve.

Other objects of this invention will become apparent hereinafter from the specification and claims.

This invention consists of the new and improved construction and combination of parts, to be more fully described hereinafter and the novelty of which will be particularly pointed out and distinctly claimed.

In the accompanying drawing to be taken as part of this specification, there are clearly and fully illustrated two preferred embodiments of this-invention in which drawing:

Figure 1 is a view in longitudinal cross section of a valve embodying the invention and shown operatively connected in a refrigeration system which is diagrammatically illustrated, and

Fig. 2 is a view in longitudinal section of a part of the valve of Fig. 1; but having a different construction of valve operating means.

Referring to the drawing by characters of reference, the numeral I refers to a compressor driven by a motor 2. Refrigerant from the compressor I is conducted through a conduit 3 to a condenser 4 and thence by a conduit 5 to a receiver 6. From the receiver 6 refrigerant fluid passes through a conduit 1 to an expansion valve 8. From the expansion valve 8 the refrigerant passes into an evaporator 9 and returns to the suction side of the compressor I through a conduit In.

The system thus far described is the standard well-known compression and expansion refrigeration cycle.

The expansion 8 comprises a casing ll having a longitudinal passageway l2 therein including a valve port l3 and having an inlet port l4 and an outlet port 15. The casing II has an enlarged end portion l6 having an annual recess I! therein. Ahollow projection [8 extends downward from the enlarged end portion I 6 and includes the inlet port l4. The annular recess l1 communicates with the inlet port I4 by a passageway iii. A passageway 20 connects the annular recess I! with another passageway 2| communicating through the valve port l3 with the passageway l2. A lateral hollow projection 22 from the cas- 10 Claims. (Cl. 62-8) ing H includes the outlet port l5 which communicates with the passageway l2. A valve carrier member 23 is positioned in the passageway 12 and is operable for reciprocal movement therein. A valve 24 is secured to and extends from the valve carrier member 23 and seats in closed position upon the-valve port I3, the valve carrier member 23 being urged towards a valve closed position by a spring 25. An adjustment screw 26 bears against the spring 25 and is operable to determine the force required tov open the valve 24. The adjustment screw 25 is carried by a separate portion ll of the casing which is secured to the main casing II by a screwthread connection as at 21. A cap member 28 covers the screw 26 and is secured to the portion H by a screw-threaded connection as at 29. A cylindrical end member '30 is carried by and aflixed to the annular rim 3| of the enlarged end portion I6, and has a lower end wall 32 closing the annular recess H. An internal wall 33 in the shape of an inverted cup having tapering side walls and an end wall portion is positioned 'within the end member 30 and has its edge carried by and hermetically sealed to the wall of the end member 30 adjacent the annular rim 3|. The end wall portion of the internal Wall 33 has an aperture therethrough of less than onehalf the area of the cross section of the end member 30 and which aperture is alined with the passageway I2. A hollow flexible bellows extends downward through and seals the aperture 34 and has a plate member 36 sealing its lower open end and extending outward to form a flanged edge portion. A spring 31 is positioned between the flanged edge portion of the plate 36 and the end wall portion of the interior wall 33 which urges the bellows 35' toward an expanded position. A plurality of longitudinal passageways 38, preferably three in number of which only two are shown, enclose push pins 39 positioned between the plate member 36 and the valve carrier member 23, push pins 39 being operative to transmit thrust from the plate member 36 to the valve carrier member 23. A flexible diaphragm 40 closes the open end of the end member 30 and is sealed thereto by a dishshaped cover member 4!. The end member 30 has an inlet port or connection 42 in its wall between the diaphragm 40 and the interior wall 33. The inlet port 42 is connected by a conduit 43 to a T 44 joining with the conduit l0 and the outlet end of the evaporator 9. A thermostatic bulb element 45 contains a fluid for translating the effect of temperature at the outlet end porto the space 41 enclosed by the dish-shaped covermember 4| and the diaphragm 49. The fluid pressure from the thermostatic bulb element 45 is operable to move the diaphragm 49 and actuate the valve 24. A push rod 48 is positioned between the bellows plate 36 and the diaphragm 49 and is operable to transmit thrust therebetween. The space enclosed between the interior wall 33 and bellows 35 and the lower wall-'32 is open to pressure from the inlet end of the evaporator 9 through the longitudinal passageways 38 surrounding the push pins 39.

In operation this form of the invention functions as follows:

The diaphragm 49 is responsive to a differential of pressure between the fluid pressure in the space 41 on one side and the pressure from the outlet end of the evaporator 9 on the, other side. The bellows 35 is responsive to the differential oi pressure between the outlet and inlet ends of the evaporator 9 and acts in opposition to movement of the diaphragm 49. As in all conventional expansion valves, an increase in temperature of the thermostatic bulb element 45 will cause pressure to be transmitted to the diaphragm 49 causing it to move downward and acting through the push rod 49, the end plate 36 and the push pins 39 to open the valve 24. However, since the other side of the diaphragm 49 is open to pressure from'the outlet end of the evaporator 9, the operations of the valve will be compensated for variations in pressure at the outlet end of the evaporator. The bellows 35 being responsive to the differential of pressure between the outlet and inlet ends of the evaporator 9 and acting in opposition to the movement of the diaphragm 49 will cause the operation of the valve to be compensated for variations in the last-named pressure differential.

This action of the bellows 35 will also function to automatically vary the superheat setting of the valve with the aforementioned compensating action (e. g. the normal tendency of the superheat setting of the valve to increase with lower suction pressure is decreased by this compensating action), but since the area of the bellows 35 is small as compared to the area of the diaphragm acts in opposition to the diaphragm 49, and

since the pressure drop across the evaporator decreases as at lower suction pressure, this tendency is decreased (so that the superheat. setting at low suction pressure would be say 11). It should be obvious then to one skilled in the art, that since the diaphragm 49 responds to the difference of pressure between the bulb 45 and the outlet end of the evaporator 9 the operation of the valve will be compensated for fluctuations in pressure drop across the evaporator 9 and that the operation of the bellows 35 as heretofore described will produce. the described adjustment of the valve superheat setting.

In Fig. 2 the construction of the valve is altered slightly to provide a gas" charged valve. The lower wall 32 of the cylindrical end member 39 has an annular depression l1 therein to which is affixed the inner cup-shaped wall 33. The spring 3? of the principal form of the invention (Fig. 1) is removed and replaced by a spring 31 positioned between the dish-shaped cover member 4i and the diaphragm 49. The thermostatic bulb element 45 is replaced by a section of helical tubing 95 which performs the same function but with a greater heat transfer area as is re-.

as described for the form shown in Fig. 1 with the same features of compensation and superheat adjustment.

What is claimed and is desired to be secured by Letters Patent of the United States is:

1. In an expansion valve for controlling the flow of a refrigerant medium to a refrigerant evaporator, a casing having a passageway therethrough including a valve port, and having an inlet and an outlet port, a valve carrier member within said casing positioned for reciprocal movement, a valve secured to and extending from said valve carrier member, a spring urging said valve carrier member toward valve closed position, a bulb element containing a thermostatic fluid and adapted for translating the effect of the temperature of the outlet end portion of the evaporator into fluid pressure; means adapted for response to the differential between said fluid pressure and the pressure at the outlet end of the evaporator and operable to actuate said valve, means adapted for response to the differential of pressure between the inlet and the outlet of the through including a valve port, and having aninlet and an outlet port, a valve carrier member within said casing positioned for reciprocal movement, a valve secured to and extending from said valve carrier member, a spring urging said valve carrier member toward valve closed position, an-

adjustment screw bearing against said spring and operable to determine the force required to open said valve, a bulb element containing a thermostatic fluid and adapted for translating the effect of the temperature of the outlet end portion of the evaporator into fluid pressure, a flexible diaphragm carried by said casing and operable through a push rod to actuate said valve,.

said diaphragm being adapted for response to the diiferential between said fluid pressure and the pressure at the outlet end of the evaporator, a flexible bellows carried by said casing and operable to resist movement of said diaphragm, said bellows being adapted for response to the difierentlal of pressure between the inlet and the out-- let ends of the evaporator, and said diaphragm and said bellows being jointly operable to compensate for variations in said.last-named pressure differential in the operation of said valve 3. In an expansion valve for controlling the flow of a refrigerant medium to a refrigerant evaporator, a casing having a passageway therethrough including a valve port, and having an inlet and an outlet port, a valve carrier member within said casing positioned for reciprocal movement, a valve secured to and extending from said valve carrier member, a spring urging said valve carrier member toward valve closed position, an adjustment screw bearing against said spring and operable to determine the force required to open said valve, a bulb'elementcontaining a thermostatic fluid and adapted for translating an aperture therethrough, a flexible bellows sealing said aperture; said dish-shaped cover member, said flrst-named wall portion, said diaphragm and said inner wall portion and bellows defining three chamber portions within said end portion, a, thrust rod member positioned between said diaphragm and said bellows and operative to transmit thrust therebetween, one or more thrust pins positioned between said bellows and said valve carrier member, said end portion having an inlet port in the middle chamber portion adapted to be connected to and receive pressure from the outlet end of the evaporator, said diaphrgam being adapted for response to the difierential of pressure between said fluid pressure on one side and evaporator outlet pressure on the other side and operable to actuate said valve, said end chamber adjacent said bellows being open to pressure from the inlet end of the evaporator so that said bellows is arranged for response to the differential of pressure between the inlet and outlet ends of the evaporator and acts in opposition to said diaphragm, and said diaphragm and said bellows being jointly operable to compensate for variations in said last-named pressure diiferential in the operation of said valve and being further operable to automatically vary the superheat setting of said valve with said compensating operation.

a. In an expansion valve for controlling the flow of a refrigerant medium to a refrigerant evaporator, a casing having a passageway therethrough including a valve port and having an inlet and an outlet port, said casing having an enlarged end portion having an annular recess therein, a projection extending from said enlarged end portion and including said inlet port, said annular recess intercommunicating with said inlet port and said passageway, a lateral projection from said casing including said outlet port, said outlet port communicating with said passageway, a valve carrier member in said passageway positioned for reciprocal movement, a valve secured to and extending from said valve carrier member, a spring urging said valve carrier member toward valve closed position, an adjustment screw bearing against said spring and operable to determine the force required to open said valve, a cylindrical and member carried by and aflixed to the annular rim of said enlarged end portion 6 and having a wall closing said annular recess, an interior wall in said end member in the shape of an inverted cup and having its edge carried by and hermetically'sealed to the wall of said end member adjacent said annular rim, an aperture through said interior wall, a hollow flexible bellows extending downward through and seal-; ing said aperture and having a plate member; sealing the lower open endof said bellows, a

spring positioned between said plate member and said interior wall urging said bellows toward an expanded position, one or more longitudinal passageways in said casing enclosing push pins positioned between said plate member and said valve carrier member for operation of said valve, a flexible diaphragm closing the open end of said end member and sealed thereto by a dish-shaped cover member, said end member having an inlet port in its wall between said diaphragm and said interior wall, said last named inlet port being adapted to be connected to and receive pressure from the outlet end of the evaporator, a thermostatic bulb element containing a fluid and adapted for translating the effect .of temperature at the outlet end portion of the evaporator into fluid pressure, said fluid pressure being transmitted to the space enclosed by said dish-shaped cover member and said diaphragm to actuate said diaphragm, a push rod positioned between said bellows plate and said diaphragm, the space enclosed by said interior wall and bellows and said lower wall being open to pressure from the inlet end of the evaporator through said one or more longitudinal passageways enclosing said push pins; said diaphragm being adapted to respond to the differential pressure between said fluid pressure on one side and evaporator outlet pres sure on the other side and operable to move said valve by acting through said push rod, said plate member, and said push pins; said bellows being adapted to respond to the differential of pressure between the inlet and outlet ends of the evaporator and acting in opposition to said diaphragm, and said diaphragm and said bellows being jointly operable to compensate for variations in said last-named pressure differential in the operation of said valve and being further operable to automatically vary the superheat setting of said valve with said compensating operation.

5. In an expansion valve for controlling the flow of a refrigerant medium to a refrigerant evaporator, a casing having a passageway therethrough'including a valve port and having an inlet and an outlet port, said casing having an enlarged end portion having an annular recess therein, a projection extending from said enlarged end portion and including said inlet port, said annular recess intercommunicating with said inlet port and said passageway, a lateral projection from said casing including said outlet port, said outlet port communicating with said passageway, a valve carrier member in said passageway positioned for reciprocal movement, a valve secured to and extending from said valve carrier member, a spring urging said valve carrier mem'ber toward valve closed position, an adjustment screw bearing against said spring and operable to determine the force required to open said valve, a cylindrical end member carried by and afllxed to the annular rim of said enlarged end portion and having a wall closing said annular recess, said wall having an annular recess therein, an interior wall in said end 16 member in the shape of an inverted cup and having its edge carried by and I hermetically sealed to said wall along said last-named annular hollow flexible bellows extending downward through and sealing said aperture and having a plate member sealing the lower open end of said bellows,- one or more longitudinal passageways in said casing enclosing push pins positioned between said plate member and said valve carrier member for operation of said valve, a flexible diaphragm closing the open end of said end member and sealed thereto by a dish-shaped cover member, 'a spring positioned between said diaphragm and said dish-shaped cover member urging said diaphragm toward a downward position, said end member having an inlet port in its wall, said last-named inlet port being adapted to be connected to and receive pressure from the outlet end of the evaporator, a thermostatic bulb element containing a fluid and adapted for translating the effect of temperature at the outlet end portion of the evaporator into gaseous pressure,

said gaseous pressure being transmitted to the .valve by-acting through said push rod, said plate member, and said push pins; said bellows being adapted to respond to the differential of pressure between the inlet and outlet ends of the evaporator and acting in opposition to said diaphragm, and said diaphragm and said bellows being jointly recess, an aperture through said interior wall, a

. 8 e '7. An expansion'valve as defined in claim 6 wherein the pressure responsive means is interposed in position for transmission of motion from said temperature responsive means to said valve member.

8. In an expansion valve for controlling the flow of a refrigerant medium to a refrigerant evaporator, a casing having an inlet and an out- .let and an interconnecting passageway therebetween, a valve member controlling flow through said passageway, means biasing said valve member toward a valve closed vposition, temperature responsive means for moving said valve member toward an open position, and

means including a pressure responsive member adapted to respond to the differential of pressure across the refrigerant evaporator and operable to vary automatically the superheat setting ofsaid valve in accordance with variations in said pressure differential.

9. In an expansion valve for controlling the Y L flow'of a refrigerant medium to-a refrigerant evaporator, a casing having an inlet and an outlet and an interconnecting passageway therebetween, a valve member controlling flow through said passageway, means biasing said valve member toward a valve closed position, responsive 1 means for moving said valve member toward an open position; said responsive means comprising a pressure responsive member adapted to respond on one side to' the pressure at the outlet end of the refrigerant evaporator, and thermooperable to compensate, for variations in said last-named pressure diflerential in the operation of said valve and being further operable to automatically vary the superheat setting of said valve with said compensating operation.

6. In an expansion valve for controlling the flow of a refrigerant medium to a refrigerant evaporator, a casing having an inlet and an outlet and an interconnecting passageway therebetween, a valve member controlling flow through said passageway, means biasing said valve member toward a valve closed position, temperature responsive means for moving said valve member I toward an open position, and pressure responsive means adapted to vary automatically the superheat setting of said valve in accordance with the differential of pressure across the refrigerant evaporator.

static means operable to apply a valve opening force to the other side of said pressure responsive member; and means including a pressure responsive member adapted to respond to the difierential of pressure across the refrigerant evaporator and operable to vary automatically the superheat setting of said valve in accordance with variations in said pressure diiferential. 10. An expansion valve as defined in claim- 9 wherein the last-named pressure responsive member is interposed for transmission of motionfrom said thermostatic means to said valve member;

FRANKLYN Y. CARTER.

- REFERENCES orrnn The following references are of record in the flle of this patent;

UNITED s'rA'rns PATENTS Number Name Date 2,182,718 Anderson Dec. 5, 1939 2,259,280 Wile Oct. 14, 1941 2,415,338 Carter 'Feb. 4, 1947 Winchester Sept. 14, 1948 

